Previous Abstract | Next Abstract
Printable Version
A63
October 17, 2009
9:00 AM - 11:00 AM
Room Area F
Evaluation of the LMA Supreme™: A Sizing and Troubleshooting Study
  *  Allan J. Goldman, M.D., Daniel Langille, C.R.N.A., Peter Freund, M.D., Michael Flacco, M.D.
Department of Anesthesiology, University of Washington Medical Center, Seattle, Washington
Introduction:

The LMA Supreme(TM) (SLMA) is a new disposable supraglottic airway, which combines the features of the LMA Proseal(TM) (gastric access tube) and Fastrach(TM) (fixed curve shaft). All LMA manufacturers' sizing recommendations are based upon patient weights. Early in our SLMA evaluation, we experienced occasional failures using those weight guidelines. We then observed that the shape and length of the SLMA fixed curve shaft is similar to a Guedel oral airway [fig. 1]. We proposed that using an oral airway-sizing guide might offer a better method for selecting the correct SLMA size. A secondary outcome from our sizing study was identifying which maneuvers improved the SLMA's fit.

Method:

We prospectively collected insertion data from 100 patients. After a propofol induction, we waited till there was lack of response to a jaw thrust before inserting the SLMA. The SLMA size was chosen according to traditional oral airway size selection (angle of jaw to corner of the mouth).

80 mm oral airway = #3 Supreme

90 mm oral airway = #4 Supreme

100 mm oral airway = #5 Supreme

If the choice was between two sizes, we chose the smaller device. If after inserting and taping the SLMA in place, the fixation tab was pressing on the upper lip, we then changed the SLMA to the next bigger size. A proper fit was determined to be [1]: fixation tab .5-2.5 cm from upper lip, tidal volume > 8ml/kg, oropharyngeal leak pressure > 20 ml/kg, and a positive suprasternal notch test [2].

If the fit was poor, one of the following maneuvers was performed: deeper insertion, an up-down maneuver (slowly withdrawing the inflated mask 5-6cm and reinserting) [3], or exchanging the device for a different size.

Results:

Size #3 was chosen for women 77% of the time, and size #4 was chosen for men 77% of the time (table 1). In the remainder of patients, the next larger size was chosen.

In 5 patients (5%) the device was removed and exchanged for another size (table 1). The SLMA was an effective airway in all patients in this study.

The up-down maneuver gave a better fit in 27% of the patients.

Discussion:

Oral airway sizing is an effective method for choosing the correct SLMA size, and is a measurement already familiar to most anesthesia practitioners. The up-down maneuver improved SLMA fit in 27% of the patients. This maneuver is performed with the LMA Fastrach(TM) to reposition a downfolded epiglottis, and may also work similarly with the SLMA. Further studies to confirm this maneuver's efficacy with the SLMA are needed.[figure1][table1]References:

1. The LMA Supreme Instruction Manual 2007

2. Connor et. al. Assessing ProSeal Laryngeal Mask Positioning: The Suprasternal Notch Test. A&A 2002; 94: 1374-75

3. Goldman et. al. The LMA CTrach in Airway Resuscitation. Anaesthesia 2006; 61: 975-77.

From Proceedings of the 2009 Annual Meeting of the American Society Anesthesiologists.
Table 1
Mask SizeWomenMen
#343 (77%)-----------
#413 (23%)34 (77%)
#5-----------10 (23%)
Changed Mask Size
3>42 (4%)-----------
4>31 (2%)-------------
4>5----------2 (5%)
5>4------------------------
Figure 1